Method for control of fluid loss and gas migration in well cementing

ABSTRACT

This invention discloses a composition and a method of using the composition to cement a borehole penetrating a subsurface earth formation. The composition, the random polymerization product of two or three different vinyl-containing monomers including a vinylamide morpholine derivative, operates to reduce fluid loss from the cement slurry used to cement the borehole to the subsurface formation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the cementing of wells which penetratesubterranean formations. The invention further relates to a compositionfor and a method of cementing a well with a slurry of hydraulic cementin water whereby loss of fluid from the slurry is reduced and movementof gas into the slurry from a subterranean formation adjacent the slurryis substantially reduced if not eliminated.

2. Related Art and Problem Solved

It is known in the art of well cementing, to position a sheath ofhardened cement in the annular space between a well pipe, such as acasing, and the walls of a wellbore which penetrates a subterraneanformation wherein the purpose of the sheath is to support the casing inthe wellbore and to prevent the undesirable movement of formationfluids, i.e., oil, gas and water, within the annular space betweensubsurface formations and/or to the surface of the earth. It is knownthat the process of positioning the sheath is referred to as primarycementing.

Thus, according to the known process of primary cementing, a slurry ofhydraulic cement in water is formed, the slurry is pumped down thecasing and circulated up from the bottom thereof in the annulus to adesired location therein and then permitted to remainundisturbed--static--in the annulus for a time sufficient to enable thehydraulic cement to react with the water in the slurry, i.e., to set, tothereby position the sheath of hardened cement.

The slurry of cement, when first placed in the annulus, acts as a trueliquid and wills therefore, transmit hydrostatic pressure. Thus,sufficient hydrostatic pressure is exerted, as a feature of the processof primary cementing, to balance the pressure of any gas in theformation to prevent the movement of gas from the formation into andthrough the slurry in the annulus. Movement of gas from a formation intoand through a cement slurry in an annulus is referred to in the art asgas migration.

Gas migration can result in movement of gas in the slurry from oneformation to another or even to the surface of the earth. Such movementcan cause loss of control of pressure and result in a blowout. Asmentioned previously, gas migration can be controlled if sufficientpressure can be transmitted through the slurry. However, loss of controlcan be experienced and gas migration can occur if the slurry does notpossess the properties of a true liquid and is unable to transmithydrostatic pressure.

Before a slurry of hydraulic cement sets into a hardened mass havingcompressive strength, events take place which cause the slurry to losethe ability to transmit hydrostatic pressure. One of the events is theloss of liquid from the slurry to the formation. Another event is thedevelopment of static gel strength in the slurry.

It seems clear that the loss of water from a slurry of cement willdiminish the ability of the slurry to transmit hydrostatic pressure. Theability to control water loss becomes more difficult as the temperatureincreases, especially at temperatures greater than about 200 degrees F.It is thus an object of this invention to provide a composition for anda method of reducing liquid loss from a slurry of hydraulic cement attemperatures greater than about 200 degrees F.

When a slurry of hydraulic cement becomes static it begins to develop aproperty known in the art as static gel strength, or simply gelstrength. (In this regard, note Sabins, et al., "The Relationship ofThickening Time, Gel Strength, and Compressive Strength of OilwellCements," SPE Production Engineering, March 1986, pages 143-152.)

Gel strength is not compressive strength. Thus, as a slurry of hydrauliccement sets into a hardened mass having compressive strength, it isbelieved that the hardening process experiences phases which arerelevant to the phenomenon of gas migration. (See Eoff et al, U.S. Pat.No. 5,339,903.) In the first phase of the process, it is believed thatthe slurry contains sufficient liquid to enable the slurry to possessthe characteristics of a true liquid. Accordingly, during the firstphase, the slurry can transmit hydrostatic pressure and gas migrationcan be prevented by applying sufficient hydrostatic pressure which istransmitted against a gas-containing formation to thereby prevent themovement of gas from the formation into the slurry.

During the first phase of the process, some of the liquid in the slurryis lost--this is referred to as fluid loss--and the slurry begins tostiffen due to the formation of a gel structure. During this firstphase, even though fluid loss and gel formation do occur, it is believedthat the setting cement retains the ability to transmit hydrostaticpressure. Accordingly, gas migration can be prevented so long as theslurry exhibits the properties of a true liquid and so long as thestiffness of the gel structure--referred to as gel strength--is lessthan or equal to a certain value which has been referred to in the artas the first critical value. The first critical value is believed to beabout 100 lb_(F) /100 sq.ft.

In the second phase of the hardening process, the gel strength of theslurry exceeds the first critical value and continues to increase; fluidloss may continue, although at a rate much lower than that experiencedin the first phase. During the second phase, it is believed that thesetting cement loses the ability to transmit full hydrostatic pressure.Accordingly, gas migration may not be prevented during the second phasebecause the gel strength of the slurry may be too high to permit fulltransmission of hydrostatic pressure, but too low to resist pressureexerted by gas in the formation against the slurry. This conditionexists until the gel strength increases to a value which has beenreferred to in the art as the second critical value, which is highenough to resist pressure exerted by gas in the formation against theslurry. The second critical value is believed to be about 500 lb_(F)/100 sq.ft.

In the third phase of the hardening process, gas migration is preventedbecause gel strength is equal to or greater than the second criticalvalue. The cement continues to harden until it attains a compressivestrength deemed sufficient to enable further operations in the wellbore.

It is noted that Sabins, et al., mentioned above, provide a discussionand a description of a method and apparatus to experimentally determinegel strength value.

In view of the above, in order to minimize gas migration, it isdesirable that maximum fluid loss, if any, should occur prior to thebeginning of the second phase of the cement hardening process; that thefirst phase should continue over an extended period of time; and thatthe second phase should be completed in a short period of time.

The time required for a slurry of hydraulic cement to attain the firstcritical value from the time the slurry becomes static has been definedin the art as "Zero Gel Time," and the time required for a slurry toattain the second critical value from the time it attains the firstcritical value has been defined in the art as "Transition Time."

It is thus another object of this invention to provide a composition forand a method of extending Zero Gel Time of a slurry for a timesufficient to enable the rate of fluid loss from the slurry to declineto a substantially constant value and to accelerate Transition Time.

It is a further object of this invention to provide a method ofcementing a wellbore which penetrates a gas-containing subterraneanformation whereby gas migration at temperatures up to 400 degrees F. andparticularly above 200 degrees F. is reduced if not eliminated.

A cement having an extended Zero Gel Time, which is a stated object ofthis invention, is referred to herein as a "low gel strength cement." Itis believed, in addition to the use in primary cementing as describedabove, that a low gel strength cement finds particular use in remedialcementing practices such as in placement thereof by coil tubing and dumpbailer applications.

SUMMARY OF THE INVENTION

It has now been discovered that a polymer composition comprising therandom polymerization product of a vinylamide morpholine derivative withat least one and, preferably, two other different vinyl-containingmonomers selected from monomers within the group consisting of avinylamide derivative, an N-vinyl,2-ketoheterocyclic derivative and avinylacid derivative, when added to a slurry of hydraulic cement madewith either fresh or salt water, is effective to reduce fluid loss fromand modify the gel strength of the slurry. It is believed that the fluidloss control and gel strength modification properties of the compoundare effective at temperatures of up to about 400 degrees F.,particularly at temperatures in the range of from about 80 to about 200degrees F. and more particularly in the range of from about 80 to about180 degrees F. The fluid loss control and gel strength modificationproperties of the polymer composition render the compound very useful ina method of cementing a wellbore which penetrates a subterraneangas-containing formation whereby migration of gas from the formationinto and through the slurry in the wellbore is reduced.

The vinylamide morpholine derivatives useful herein are selected fromcompounds represented by the general formula ##STR1##

The vinylamide derivatives useful herein are selected from compoundsrepresented by the general formula ##STR2##

The N-vinyl,2-ketoheterocyclic derivatives useful herein are selectedfrom compounds represented by the general formula ##STR3##

The vinylacid derivatives useful herein are selected from compoundsrepresented by the general formula ##STR4##

The polymer composition of this invention is sometimes referred toherein as the gel strength modifier/fluid loss additive of thisinvention. Thus, in one aspect, the polymer composition of thisinvention is a copolymer made by reacting a monomer selected fromcompounds within the scope of formula (1), the vinylamide morpholinederivative, with a monomer selected from compounds within the scope offormula (2), the vinylamide derivative, or with a monomer selected fromcompounds within the scope of formula (3), theN-vinyl,2-ketoheterocyclic derivative or with a monomer selected fromcompounds within the scope of formula (4), the vinylacid derivative.

In another aspect, the polymer composition is a terpolymer made byreacting a vinylamide morpholine derivative, formula (1), with twodifferent monomers selected from compounds within the scope of formulas(2), (3) and (4) wherein each of the two different monomer reactants isselected from a different vinyl-containing structure as defined informulas (2), (3) and (4), above. For example, if one of the twodifferent monomers is selected from compounds within the scope offormula (2), then the second monomer must be selected from compoundswithin the scope of either formula (3) or formula (4).

In a preferred embodiment, the polymer composition is a copolymer madeby reacting a monomer within the scope of formula (1) with a monomerwithin the scope of formula (2).

In another preferred embodiment the polymer composition is a terpolymermade by reacting a monomer within the scope of formula (1) with amonomer within the scope of formula (2) and with a monomer within thescope of formula (4).

The polymer composition of this invention and the method of preparationthereof should be distinguished from the method of making graft polymersand the resulting product. In this regard grafting polymers on a naturalproduct backbone is a known process. An example of the process is foundin Fry, et al., U.S. Pat. No. 4,703,801 and Fry, et al. U.S. Pat. No.4,676,317 each of which disclose a natural product backbone, lignin orlignite, having grafted thereto polymers including homopolymers andcopolymers of 2-acrylamido-2-methylpropanesulfonic acid andN,N-dimethylacrylamide. The Fry, et al., polymer graft is disclosed tobe useful in a cementing composition as a fluid loss additive. Fry, etal., do not mention modification of slurry gel properties, zero geltime, transition time or gas migration.

Eoff et al., U.S. Pat. No. 5,339,903, disclose grafting polymer groupsto tannin, a natural product backbone, wherein the polymer groupsconsist of at least two, and preferably three, vinylamide derivatives.Eoff et al. do mention modification of slurry gel properties, zero geltime, transition time and gas migration.

Another example of the use of a polymer grafted natural product backbonein a well cementing composition is provided in Huddleston, et al., U.S.Pat. No. 5,134,215 and Huddleston, et al., U.S. Pat. No. 5,147,964.Huddleston, et al., each disclose a wattle tannin backbone grafted with2-acrylamido-2-methylpropanesulfonic acid or with2-acrylamido-2-methylpropanesulfonic acid and acrylamide. Huddleston, etal., disclose their polymer grafted tannin to be useful as a fluid lossadditive in a cementing composition, but they do not mentionmodification of slurry gel properties, zero gel time, transition time orgas migration.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

By this invention, there is provided a polymer composition, a hydrauliccement slurry composition containing the polymer composition and amethod of using the hydraulic cement slurry composition to cement apipe, such as a casing, in a wellbore whereby fluid loss is reduced andgas migration in the cement slurry is eliminated or at leastsubstantially reduced. Accordingly, when a pipe is cemented in awellbore which penetrates a gas-containing subterranean formation, thecomposition of this invention, when placed by conventional stepsadjacent the gas-containing formation, exhibits low fluid loss and actsto eliminate, or to at least substantially reduce, gas migration, i.e.,the movement of gas from the formation into and through the cementslurry.

As mentioned, gas migration is a problem to be avoided because it leadsto communication by way of the well annulus between formations and/or tothe surface and is thus a source of surface and subsurface blowouts.

Gas moving in a hardening cement slurry can create permanent channels inthe set cement. The gas channels must be filled with cement in aseparate remedial cementing technique called squeezing in order toprevent the communication mentioned above.

Gas migration is caused by the inability of the cement slurry placed inthe zone adjacent the gas-containing formation to resist the pressure ofthe gas in the formation. Accordingly, the gas moves from the formationinto and through the slurry.

The hydraulic cement slurry composition of this invention is formulatedto provide a Zero Gel Time of greater than about one hour and aTransition Time of less than about one hour, whereby the time in whichthe hardening cement slurry can transmit hydrostatic pressure ismaximized, and the time in which gas migration can occur is minimized.Furthermore, fluid loss from the hydraulic cement slurry composition ofthis invention is less than about 100 cc/30 minutes and maximum fluidloss is believed to occur prior to the attainment of Zero Gel Time.

Cement slurries, which do not contain gel strength modifiers, such asthose disclosed and claimed herein, ordinarily have Zero Gel Times ofmuch less than one hour. This means that the fluid loss rate from such aslurry will still be relatively high after the slurry has reached thesecond critical value. This high fluid loss rate combined with theinability of the gelled slurry to transmit hydrostatic pressure greatlyincreases the probability that gas migration will occur.

The hydraulic cement slurry composition of this invention is comprisedof hydraulic cement, water, present in an amount in the range of fromabout 35 to about 60 percent water by weight of dry cement, and the gelstrength modifier/fluid loss additive of this invention, present in anamount in the range of from about 0.1 to about 1.5, preferably 0.3 toabout 1.0 and still more preferably from about 0.5 to about 0.8 percentadditive by weight of dry cement. Mix water concentrations greater thanthose mentioned can be employed in the presence of extenders and/orultra fine and slag cements.

The slurry, in addition to the above ingredients, also preferablyincludes a high temperature set time retarder such as sodium or calciumlignosulfonate or organic acids, such as citric, tartaric or gluconicacid, or mixtures of such acids and lignosulfonates present in an amountin the range of from about 0.5 to about 2.0 percent retarder by weightof dry cement. Furthermore, a high temperature strength regression aidsuch as silicon dioxide, can be present in the slurry in an amount inthe range of from about 0 to about 40 percent by weight of dry cement.If desired a weighting agent, such as hematite, may be included in theslurry in an amount in the range of from about 10 percent to about 60percent by weight of dry cement.

As previously mentioned, the additive of this invention is a polymercomposition comprising the random polymerization product of a vinylamidemorpholine derivative with at least one and, preferably, two otherdifferent vinyl-containing monomers selected from monomers within thegroup consisting of a vinylamide derivative, anN-vinyl,2-ketoheterocyclic derivative and a vinylacid derivative.Accordingly, the polymer composition can be a random copolymer or arandom terpolymer. The copolymer is made by reacting a monomer selectedfrom compounds within the scope of formula (1), the vinylamidemorpholine derivative, with a monomer selected from compounds within thescope of formula (2), the vinylamide derivative, or with a monomerselected from compounds within the scope of formula (3), theN-vinyl,2-ketoheterocyclic derivative or with a monomer selected fromcompounds within the scope of formula (4), the vinylacid derivative. Theterpolymer is made by reacting a vinylamide morpholine derivative,formula (1), with two different monomers selected from compounds withinthe scope of formulas (2), (3) and (4) wherein each of the mentioned twodifferent monomer reactants is selected from a differentvinyl-containing structure as defined in formulas (2), (3) and (4),above.

It is noted that the polymer composition of this invention does notinclude a polymer made from all four of the defined structures.

Thus, the polymer composition of this invention consists of: copolymersmade from monomers within the scope of formulas (1) and (2), formulas(1) and (3) and formulas (1) and (4); and terpolymers made from monomerswithin the scope of formulas (1), (2) and (3), formulas (1), (2) and (4)and formulas (1), (3) and (4).

The vinylamide morpholine derivatives useful herein are selected fromcompounds represented by the general formula ##STR5## wherein R₁ is --Hor --CH₃ and R₂ is --CH₃ or --CH₂ CH₃ and can be positioned on any oneof the four carbons in the morpholine ring.

The vinylamide derivatives useful herein are selected from compoundsrepresented by the general formulas ##STR6## wherein R₃ is --H or --CH₃; R₅ is --H, --CH₃ or --CH₂ CH₃ ; and R₄ is --H, --CH₃, --CH₂ CH₃,--CH(CH₃)₂, --C(CH₃)₃ or --C(CH₃)₂ CH₂ SO₃ X wherein X is --H, --Na,--NH₄ or --Ca1/2.

The N-vinyl,2-ketoheterocyclic derivatives useful herein are selectedfrom compounds represented by the general formula ##STR7## wherein R₆ is--H or --CH₃ ; and m has a value in the range of 3 to 6.

The vinylacid derivatives useful herein are selected from compoundsrepresented by the general formula ##STR8## wherein R₇ is --H or --CH₃ ;Z is --PO₃ Y₂, --SO₃ Y or --CO₂ Y wherein Y is --H, --Na or --Ca1/2 andn has a value in the range of from about 0 to about 3.

In one preferred embodiment, the polymer composition of this inventionconsists essentially of the copolymerization product of the vinylamidemorpholine derivative and the vinylamide derivative, wherein R₄ is apropanesulfonic acid group, i.e., R₄ =--C(CH₃)₂ CH₂ SO₃ H, and R₁, R₂,and R₃ and R₄ are each hydrogen.

In another preferred embodiment, the polymer composition of thisinvention consists essentially of the terpolymerization product of thevinylamide morpholine derivative, the vinylamide derivative and thevinylacid derivative, wherein Z is a phosphonic acid group, i.e., n=0and Z=--PO₃ H₂, or an acrylic acid group, i.e., n=1 and Z=--CO₂ H, R₄ isa propanesulfonic acid group, i.e., R₄ =--C(CH₃)₂ CH₂ SO₃ H, and R₁, R₂,R₃, R₅ and R₇ are each hydrogen.

In still another preferred embodiment, the polymer composition of thisinvention consists essentially of the terpolymerization product of thevinylamide morpholine derivative, the N-vinyl,2-ketoheterocylicderivative and the vinylacid derivative, wherein m is 3 or 5, Z is aphosphonic acid group, i.e., n=0 and Z=--PO₃ H₂, or an acrylic acidgroup, i.e., n=1 and Z=--CO₂ H, and R₁, R₂, R₆ and R₇ are each hydrogen.

The mole ratio of the vinylamide derivative to the vinylamide morpholinederivative in the polymer composition is an amount in the range of fromabout 0 to about 4.5 moles of the vinylamide derivative per mole of thevinylamide morpholine derivative. This range recognizes the situationinvolving the complete absence of the vinylamide derivative.

Likewise, the mole ratio of the N-vinyl,2-ketoheterocylic derivative tothe vinylamide morpholine derivative in the polymer composition is anamount in the range of from about 0 to about 4.5 moles of theN-vinyl,2-ketoheterocylic derivative per mole of the vinylamidemorpholine derivative. This range recognizes the situation involving thecomplete absence of the N-vinyl,2-ketoheterocylic derivative.

It was previously mentioned that the terpolymer can include both thevinylamide derivative and the N-vinyl,2-ketoheterocylic derivative. Inthis situation the sum of the molar concentrations of the vinylamidederivative and the N-vinyl,2-ketoheterocylic derivative cannot exceedthe mole ratio of 4.5 moles of the combination per mole of thevinylamide morpholine derivative. In view of the above, it is to beunderstood that if the molar concentration of either the vinylamidederivative or the N-vinyl,2-ketoheterocylic derivative in the polymercomposition is zero, then the concentration of the other can be anamount up to and including the 4.5 to 1 mole ratio described above. Itis to be further understood that if the molar concentrations of each ofthe vinylamide derivative and the N-vinyl,2-ketoheterocylic derivativein the polymer composition is greater than zero, then the sum of themole ratios of each with respect to the vinylamide morpholine derivativecannot exceed 4.5.

Whenever the vinylamide derivative or the N-vinyl,2-ketoheterocylicderivative is present in the polymer composition it is believed that aneffective concentration of either one can be as low as about 0.5 molesper mole of the vinylamide morpholine derivative. However, subject tothe 4.5 mole ratio limit mentioned above, the concentration of eitherone is preferably in the range of from about 1.5 to about 3.0 and mostpreferably from about 2 to about 2.5 moles of the vinylamide derivativeand/or the N-vinyl,2-ketoheterocylic derivative per mole of thevinylamide morpholine derivative.

The mole ratio of the vinylacid derivative to the vinylamide morpholinederivative in the polymer composition is an amount in the range of fromabout 0 to about 4.5 moles of the vinylacid derivative per mole of thevinylamide morpholine derivative. This range recognizes the situationinvolving the complete absence of the vinylacid derivative up to themaximum concentration of the vinylacid derivative when the polymercomposition is a copolymer including only it and the vinylamidemorpholine derivative. However, when the polymer composition is aterpolymer including the vinylacid derivative, then the maximumconcentration of the vinylacid derivative is 0.55 and, preferably, inthe range of from about 0.005 to about 0.45 and most preferably fromabout 0.01 to about 0.35 moles of the vinylacid derivative per mole ofthe vinylamide morpholine derivative.

It was mentioned above that the polymer composition of this inventioncan control fluid loss from and modify the gel strength of a slurry ofhydraulic cement in both fresh water and salt water. In this regard, ithas been discovered that the operability of the polymer composition ofthis invention to reduce fluid loss from and modify gel strength offresh water and salt water cement slurries is, to a great extent, afunction of the content of the compound. Thus, if a fresh water slurryis to be treated, then the polymer composition of this invention to beutilized is preferably made by polymerizing the vinylamide morpholinederivative with either the vinylamide derivative or theN-vinyl,2-ketoheterocylic derivative or mixtures thereof employing themole ratios disclosed above. However, if a salt water slurry is to betreated, then the polymer composition to be utilized is preferably madeby terpolymerizing the vinylamide morpholine derivative with either thevinylamide derivative or the N-vinyl,2-ketoheterocylic derivative andthe vinylacid derivative employing the mole ratios disclosed above.

It is noted that the polymer composition of this invention when madewith the vinylacid derivative is effective to reduce fluid loss andmodify gel strength in both fresh and salt water slurries. However, ithas been observed that the inclusion of the vinylacid derivative in thepolymerization recipe produces a polymer composition which, in additionto the fluid loss control and gel strength modification properties, alsoacts to retard the set time of a cement slurry. Accordingly, when freshwater slurries are to be treated, it is preferred that the polymercomposition employed should not include the vinylacid derivative in thepolymerization recipe.

The upper limit of the mole ratio of the vinylacid derivative to thevinylamide morpholine derivative in the recipe for making the terpolymeraspect of the polymer composition was disclosed to be about 0.55 molesof the vinylacid derivative per mole of the vinylamide morpholinederivative. At this limit, the fluid loss effect on salt water slurriesremains quite satisfactory, but set retardation may be excessive from anoperational point of view.

The preferred vinylamide morpholine derivative is acryloylmorpholine,the preferred vinylamide derivative is2-acrylamido-2-methylpropanesulfonic acid, the preferredN-vinyl,2-ketoheterocylic derivative is N-vinyl pyrrolidone and thepreferred vinylacid derivative is vinylphosphonic acid.

Some specific compounds within the scope of formula (1) believed to beuseful herein include acryloylmorpholine and methacryloylmorpholine.

Some specific compounds within the scope of formula (2) believed to beuseful herein include 2-acrylamido-2-methylpropanesulfonic acid,acrylamide, methacrylamide, N-methylacrylamide, N-i-propylacrylamide,N-i-propylmethacrylamide, N-t-butylacrylamide, N-t-butylmethacrylamide,N,N-dimethylacrylamide and N,N-dimethylmethacrylamide.

Some specific compounds within the scope of formula (3) believed to beuseful herein include N-vinyl pyrrolidone, and N-vinyl caprolactam.

Some specific compounds within the scope of formula (4) believed to beuseful herein include vinyl phosphonic acid, acrylic acid andvinylsulfonic acid.

The polymer composition of this invention is water soluble, and can beemployed in the liquid or solid (dry) state and in the acidic or baseneutralized form.

The polymer composition of this invention is prepared by forming anaqueous solution of the disclosed vinyl derivatives and causing thederivatives to react in the presence of an effective amount of asuitable water soluble initiator at atmospheric pressure and at atemperature in the range of from about 40 to about 50 degrees Celsius.The total weight of the disclosed vinyl derivatives, in the combinationsand mole ratios disclosed above, is present in the mentioned aqueoussolution in an amount in the range of from about 5 to about 20,preferably 7 to 15 and still more preferably from about 9 to about 13percent by total weight of solution.

Accordingly, to obtain the polymer composition of this invention havinga molecular weight in the desired range the mole ratio of the totalnumber of moles of vinyl derivatives in the reaction mass per mole ofinitiator is believed to be an amount in the range of from about 125 toabout 135 wherein the reaction is conducted at the temperatures andpressure set out above.

Addition of initiator to the reaction mass is conveniently effected inwater solution. For example, in one preferred embodiment featuringacryloylmorpholine, 2-acrylamido-2-methylpropanesulfonic acid andvinylphosphonic acid as the reactants, the initiator, sodium persulfate,is added to the reaction mass in a 14.5 percent by weight aqueoussolution. As such, when the combined weights of the reactants, initiatorand solution water are considered, sodium persulfate is present in anamount in the range of from about 0.05 to about 0.2, preferably fromabout 0.075 to about 0.15 and more preferably about 0.09 to about 0.12percent by weight of the entire reaction mass.

The preferred initiator is sodium persulfate and functional equivalentsthereof as disclosed in U.S. Pat. No. 4,726,906.

The term "cement" as used herein is intended to include those compoundsof a cementitious nature which are described as hydraulic cements. Suchcompounds include, for example, Portland Cement in general andparticularly Portland Cements of API Classes G and H, although other APIclasses can be utilized, as well as pozzolan cements, gypsum cements,high alumina content cements, slag cements, high gel (high clay content)cements, silicate containing cements, ultrafine cements and highalkalinity cements. Portland cements and, particularly, cement of APIClasses G and H are preferred.

The aqueous fluid utilized in the cement composition can be water fromany source provided that it does not contain an excess of any compoundsthat affect the stability of the cement composition of the presentinvention. The aqueous fluid can contain various salts such as sodiumchloride, potassium chloride, calcium chloride and the like.

Other types of well known and conventional additives also can beincorporated into the cement composition to modify the properties of thecomposition. Such additives include additional fluid loss additives,viscosifiers, retarders, accelerators, dispersants, weight-adjustingmaterials or fillers and the like.

Additional fluid loss additives which may be incorporated into thecement composition of the present invention include cellulosederivatives such as carboxymethylhydroxyethyl cellulose, hydroxyethylcellulose, modified polysaccharides, polyacrylamides, polyaromaticsulfonates, guar gum derivatives, mixtures of such compounds and thelike. Numerous other compounds which may be utilized as additional fluidloss additives are well known by those skilled in cementing technology.

A retarder may be used in the cementing composition when the bottom holecirculating temperature exceeds 100 degrees F. Examples of retarderswhich can be used herein include lignosulfonates, such as calciumlignosulfonate and sodium lignosulfonate, organic acids, such as citricacid, tartaric acid and gluconic acid and mixtures thereof. The amountof retarder required will vary according to the bottom hole circulatingtemperatures and variation in the makeup of the cement itself.

The proper amount of retarder required in any particular case should bedetermined by running a "thickening time" test for the particularconcentration of retarder and cement composition being used. Such testsshould be run according to the procedures set forth in API SPEC 10 usinga device called a consistometer. Generally speaking, "thickening time"is defined in API SPEC 10 as the elapsed time from the time pumpingbegins until the cement reaches from about 70 to 100 units ofconsistency, referred to as Bearden units of consistency. Bearden unitsof consistency obtained on a pressurized consistometer are referred toas Bc units. Bearden units of consistency obtained on an atmosphericpressure consistometer are referred to as ABc units. In mostapplications the amount of retarder, if any required, will not exceedmore than about 5.0 percent by weight of the dry cement.

Dispersing agents can be utilized to facilitate using lower quantitiesof water and to promote higher set cement strength. Friction reducerswhich promote freer movement of the unset composition, and allow ease ofpumping through the annulus, if present, can be incorporated in theslurry in amounts up to about several percent by weight of dry cement.Some dual function additives, such as lignosulfonates which functionboth as a dispersant and also as a set time retarder, can beincorporated in the slurry where their use would be advantageous forcertain cementing situations.

Accelerators, such as the soluble inorganic salts in addition to calciumchloride, can be utilized in amounts up to about 8 percent by weight ofdry cement.

The cement composition also may include in particular applications,foaming agents or defoaming agents which comprise various anionic,cationic, nonionic and other surface active compounds. The amount ofsuch surface active agents added to the cement composition willtypically be in the range of from about 0.1 to about 3 percent by weightof dry cement. Generally, the selection of such additives will be withinthe skill of those knowledgeable in the art of well cementing.

Of the various types of fine aggregate which can be used, fly ash,silica flour, fine sand, diatomacious earth, lightweight aggregate andhollow spheres can be cited as typical. The use of these materials iswell understood in the art, and so long as they are compatible with thecompositions of the invention, they can be employed over wide ranges ofconcentrations.

EXAMPLES

The following examples are provided to illustrate some benefits of thecomposition and method of the present invention and not by way oflimitation thereof.

Example 1

Polymer compositions of this invention were made employing theingredients in the quantities set out in Table 1, below. The reactionswere conducted at atmospheric pressure and at the initial reactiontemperatures in the range of from 111 to 116 degrees Fahrenheit asindicated. The procedure employed to make the polymer compositions is asfollows.

About 70% of the indicated quantity of D.I. Water is placed in areaction vessel of suitable size which is equipped with a recirculatingpump and associated tubing, a mechanical stirrer, a nitrogen spargetube, an addition funnel, a temperature indicating means and a means forheating the vessel and the contents thereof. The mixer is activated tostir at 130 rpm and the indicated quantities of monomers are slowlyadded in sequence with continuous mixing until all monomers allcompletely dissolved. After all monomers are added the balance of wateris added with continuous mixing. The solution is then sparged withnitrogen at 22 liters per minute for a total of 30 minutes to excludeair (oxygen) from the reaction.

Thereafter, the nitrogen sparge rate is changed to 10 liters per minute,the stirring rate is changed to 110 rpm, the entire indicated quantityof initiator in water solution is rapidly added and the temperature ofthe reaction mass is monitored until it appears to stabilize, which isan indication of the completion of the reaction.

Thereafter, the reaction mass is recirculated until the temperature ofthe mass fully stabilizes. Then, recirculation, mixing and sparging isterminated, the temperature of the mass is adjusted to a value of about140 degrees Fahrenheit and the mass is maintained at that temperature inthe closed reaction vessel for at least about 3 hours until theviscosity of the reaction product attains a value in the range of fromabout 5000 to about 11,000 centipoises.

                                      TABLE 1                                     __________________________________________________________________________    PREPARATION OF POLYMER COMPOSITION OF THIS INVENTION                                       POLYMER                                                                             POLYMER                                                                              POLYMER                                                                             POLYMER                                                    #1    #2     #3    #4                                                         grams grams  grams grams                                         __________________________________________________________________________    ACMO  (monomer)                                                                            1406.129                                                                            18.11  78.78 12.05                                         AMPS  (monomer)                                                                            4581.259                                                                            59.15  256.75                                                                              37.73                                         VPA   (monomer)                                                                            0.0   0.0    1.44  0.00                                          AA    (monomer)                                                                            0.0   0.0    0.0   1.54                                          DI WATER     52162.85                                                                            671.65 2911.25                                                                             445.15                                        Sub Totals   58150.238                                                                           748.91 3248.22                                                                             496.47                                        SP    (initiator)                                                                          59.00 0.77   3.32  0.51                                          DI WATER     344.7 4.54   19.58 3.01                                          Sub Totals   403.7 5.31   22.9  3.52                                          Total        58553.938                                                                           754.22 3271.12                                                                             499.99                                        __________________________________________________________________________           ACMO/AMPS                                                                            ACMO/AMPS                                                                            ACMO/AMPS/VPA                                                                          ACMO/AMPS/AA                                    __________________________________________________________________________    MOLE RATIOS                                                                   MONOMERS                                                                             1/2.219                                                                              1/2.225                                                                              1/2.22/0.024                                                                           1/2.133/0.25                                    SP     129.49 127.93 129.83   134.833                                         WEIGHT PERCENTS                                                               SP (solution)                                                                        14.615 14.501 14.498   14.489                                          SP (overall)                                                                         0.101  0.102  0.101    0.102                                           ACTIVE 10.326 10.345 10.403   10.366                                          INITIAL REACTION TEMPERATURE                                                  degrees F                                                                            111    116    116      115                                             __________________________________________________________________________     Note:                                                                         1. ACMO is acryloylmorpholine.                                                2. AMPS is 2acrylamido-2-methylpropane sulfonic acid.                         3. VPA is vinyl phosphonic acid.                                              4. AA is acrylic acid.                                                        5. SP is sodium persulfate. The indicated mole ratio of SP is the sum of      the molar quantities of the monomer reactants divided by the number of        moles of SP. The indicated weight percent of SP (solution) is the             concentration of SP in the solution added to the reaction. The indicated      weight percent of SP (overall) is the concentration of SP in the entire       reaction mass.                                                                6. D.I. WATER is deionized water.                                             7. The reaction mass at this point is a liquid and has an acid pH. It can     be employed as an additive for cement to control fluid loss and modify        cement gel strength in accordance with the method of this invention.          8. The method of preparation of the additive of this invention, as shown      in this Example 1, produces a random arrangement of polymers referred to      as the polymer composition of this invention.                                 9. The weight percent ACTIVE is the total weight of monomers and initiato     as a percent of the total weight of the reaction mass.                   

Example 2

Polymer number 1 produced as described in Example 1, above, was furthertreated by converting it from the liquid acid form to the dry salt formby base neutralization. Accordingly, polymer number 1 a viscous acidicliquid, was contacted with an aqueous alkaline solution, a 30 weightpercent aqueous solution of calcium hydroxide, an example of which iscommercially available as Mississippi Lime. The pH of the solution wasadjusted to a value in the range of from about 7 to 8. Thereafter, asmall quantity of silicon solution, a release agent, was added to theneutralized solution which was then placed in a drum dryer rotating at 4revolutions per minute and operating at about 300 degrees Fahrenheit.The material was maintained in the dryer under the mentioned conditionsfor a time sufficient to produce a dried product which was then reducedto a fine powder by milling. The milled product was then used inaccordance with the method of this invention.

Example 3

Cement slurries were prepared and tested for fluid loss, consistency andrheological properties in accordance with the provisions of API SPEC 10.Polymer number 1, shown in Table 1, above, after first beingneutralized., dried and milled in accordance with Example 2, wasemployed in the slurries referred to in Tables 2A-2C. Polymer numbers 2,3 and 4, shown in Table 1, unless otherwise indicated, were employed asprepared in Example 1, in the slurries referred to made in Tables 3, 4and 5, respectively.

The quantities of "Polymer," mix water, sand and retarder, referred toin Tables 2-5, below, are expressed as percent by weight of dry APICLASS H cement unless otherwise noted.

The mix water employed, unless otherwise noted, was potable city tapwater as available in Mesquite, Texas. In some runs the mix waterincluded other ingredients which are referred to as "Additive". Thequantity of "Additive" is expressed as percent by weight of mix water.

Unless otherwise noted, footnotes 3, 4, and 5 for each of Tables 2-5 isas follows: 3. Fluid Loss was determined in accordance with theprovisions of API Spec 10, Appendix F. 4. Consistency was determined inaccordance with the provisions of API Spec 10, Section 9. 5. Rheologicalproperties were determined in accordance with the provisions of API Spec10, Appendix H using a Fann Rotational Viscometer OFI Model 800 withrotor sleeve R1, bob B1 and loaded with a 1 inch spring.

                                      TABLE 2A                                    __________________________________________________________________________    SLURRY NUMBER                                                                 38 PERCENT MIX WATER                                                                  1  2  3  4  5  6   7   8.sup.2                                                                           9.sup.2                                    __________________________________________________________________________    Polymer, %                                                                              0                                                                                0                                                                               0.3                                                                              0.4                                                                              0.5                                                                              0.5                                                                               0.6                                                                               0.6                                                                               0.8                                       Additive, %                                                                             0                                                                                0                                                                               0  0  0  2.0.sup.1                                                                         2.0.sup.1                                                                         0   0                                         Temp deg F                                                                             80                                                                               125                                                                             125                                                                              125                                                                              125                                                                              125 125 180 180                                        Fluid Loss.sup.3                                                                      1119                                                                             1200                                                                              90                                                                               54                                                                               44                                                                              104  66 112  44                                        cc/30 mm                                                                      Consistency.sup.4                                                             initial, ABc                                                                            6                                                                               10                                                                               8  9  10                                                                               7   10  9   13                                        @20 min, ABc                                                                            7                                                                               17                                                                               9  9  11                                                                               7   9   7   7                                         Rheology.sup.5                                                                600 rpm  150                                                                              220                                                                             210                                                                              275                                                                              330+                                                                             220 300+                                                                              137 209                                        300 rpm  110                                                                              181                                                                             124                                                                              165                                                                              224                                                                              135 161  77 122                                        200 rpm  94                                                                               159                                                                              90                                                                              121                                                                              165                                                                               98 118  51  89                                        100 rpm  75                                                                               130                                                                              53                                                                               71                                                                               98                                                                               58  70  32  51                                         6 rpm   23                                                                               21                                                                               7  9  12                                                                               8   10  4   5                                          3 rpm   13                                                                               14                                                                               6  6  8  7   7   3   3                                         __________________________________________________________________________

                  TABLE 2B                                                        ______________________________________                                        SLURRY NUMBER                                                                 44 PERCENT MIX WATER                                                                 10   11     12     13   14   15   16.sup.6                                                                           17.sup.7                        ______________________________________                                        Polymer, %                                                                             0.3    0.6    0.4  0.5  0.6  0.8  0.6  0.8                           Additive, %                                                                            0      0      0    0    0    0    0    0                             Temp deg F                                                                             80     80     125  125  125  180  125  180                           Fluid Loss.sup.3                                                                       78     36     62   48   42   32   70   56                            cc/30 mm                                                                      Consistency.sup.4                                                             initial, ABc                                                                           5      7      7    9    7    12   9    12                            @20 min, ABc                                                                           6      10     7    9    7    11   9    9                             Rheology.sup.5                                                                600 rpm  129    272    144  215  230  212  236  254                           300 rpm  70     149    84   123  135  125  141  155                           200 rpm  48     112    60   88   96   91   104  115                           100 rpm  27     60     36   53   55   53   61   67                             6 rpm   4      6      5    7    7    6    7    7                              3 rpm   3      5      4    5    5    4    5    5                             ______________________________________                                    

                  TABLE 2C                                                        ______________________________________                                        SLURRY NUMBER                                                                 MIX WATER.sup.10                                                                              18   19                                                       ______________________________________                                        Polymer, %        0.6    0.6                                                  Additive, %       8.sup.8                                                                              2.sup.9                                              Temp deg F.       80     80                                                   Fluid Loss.sup.3                                                              cc/30 mm          42     72                                                   Consistency.sup.4                                                             initial, ABc      15     9                                                    @ 20 min, ABc     12     5                                                    Rheology.sup.5                                                                600 rpm           151    82                                                   300 rpm           91     46                                                   200 rpm           69     34                                                   100 rpm           44     21                                                    6 rpm            5      5                                                     3 rpm            3      2                                                    ______________________________________                                         Footnotes Tables 2A-2C:                                                       .sup.1. Calcium chloride.                                                     .sup.2. Mix water was simulated sea water, an aqueous alkaline solution       consisting of 3.4% FRITZ SUPER SALT by weight of solution. FRITZ SUPER        SALT is a concentrate available from Fritz Industries, Inc., of Mesquite,     Texas. Dechlorinated water was employed to dilute the concentrate to          prepare the mix water employed in slurries 8 and 9.                           .sup.6. API Class G cement.                                                   .sup.7. API Class G cement.                                                   .sup.8. Bentonite extender.                                                   .sup.9. Sodium metasilicate extender.                                         .sup.10. Slurry 18 was made using 80.3 percent mix water and slurry 19 wa     made using 104.6 percent mix water.                                      

                  TABLE 3                                                         ______________________________________                                        SLURRY NUMBER                                                                 MIX WATER.sup.1                                                                          20   21         22     23                                          ______________________________________                                        Polymer, %   0.8    0.8        0.8  0.8                                       Additive, %  0      10.sup.2   10.sup.2                                                                           38.sup.2                                  Deg F.       180    180        180  180                                       Sand         0      35         0    35                                        Retarder     0      0.6.sup.6  0    0.6.sup.6                                 Fluid Loss.sup.3                                                              cc/30 mm     32     469        350  495                                       Consistency.sup.4                                                             initial, ABc 12     15         15   20                                        @ 20 min, ABc                                                                              11     11         11   15                                        Rheology.sup.5                                                                600 rpm      212    330+       193  245                                       300 rpm      125    215        116  140                                       200 rpm      91     155        86   100                                       100 rpm      53     92         51   58                                         6 rpm       6      15         6    10                                         3 rpm       4      11         4    8                                         ______________________________________                                         Footnotes Table 3:                                                            .sup.1. Slurry 20 was made using 44 percent mix water and slurries 21, 22     and 23 were made using 41.65 percent mix water.                               .sup.2. NaCl                                                                  .sup.6. Retarder was calcium lignosulfonate                              

                  TABLE 4                                                         ______________________________________                                        SLURRY NUMBER                                                                 MIX WATER.sup.1                                                               24         25     26     27    28    29    30                                 ______________________________________                                        Polymer, %                                                                             0.8    1.0    0.8  1.0   1.0   1.0   1.0.sup.6                       Additive, %                                                                            0      0      10.sup.2                                                                           10.sup.2                                                                            18.sup.2                                                                            38.sup.2                                                                            38.sup.2                        Temp deg F                                                                            180    180    180  180   180   180   180                              Fluid Loss.sup.3                                                                       90     34    119   80    34    30    42                              cc/30 mm                                                                      Consistency.sup.4                                                             initial, ABc                                                                           11     25     14   20    12    38    16                              @20 min,                                                                               9      12     11   20    8     6     7                               ABc                                                                           Rheology.sup.5                                                                600 rpm 277    330+   330+ 330+  295   280   300+                             300 rpm 110    181    124  165   224   135   161                              200 rpm  94    159     90  121   165    98   118                              100 rpm  75    130     53   71    98    58    70                               6 rpm   23     21     7    9     12    8     10                               3 rpm   13     14     6    6     8     7     7                               ______________________________________                                         Footnotes Table 4:                                                            .sup.1. Slurries 24 and 25 were made using 44 percent mix water and           slurries 26, 27, 28, 29 and 30 were made using 41.65 percent mix water.       .sup.2. NaCl                                                                  .sup.6. A portion of Polymer 3 used in slurry 30 was neutralized and drie     as described in Example 2, above.                                        

                  TABLE 5                                                         ______________________________________                                        SLURRY NUMBER                                                                 MIX WATER.sup.1                                                                               31   32                                                       ______________________________________                                        Polymer, %        1.0    1.0                                                  Additive, %       0      38.sup.2                                             Temp deg F.       180    180                                                  Fluid Loss.sup.3                                                              cc/30 mm          24     56                                                   Consistency.sup.4                                                             initial, ABc      11     20                                                   @ 20 min, ABc     9      10                                                   Rheology.sup.5                                                                600 rpm           277    300                                                  300 rpm           220    230                                                  200 rpm           160    170                                                  100 rpm           91     98                                                    6 rpm            11     16                                                    3 rpm            7      11                                                   ______________________________________                                         Footnotes Table 5:                                                            .sup.1. Slurry 31 was made using 44 percent mix water and slurry 32 was       made using 41.65 percent mix water.                                           .sup.2. NaCl                                                             

Example 4

Cement slurries were prepared and tested for thickening time, zero geltime, transition time and compressive strength. Polymer number 1, shownin Table 1, above, after first being neutralized, dried and milled inaccordance with Example 2, was employed in the slurries referred to inTable 6.

The quantities of "Polymer," mix water and retarder, referred to inTable 6 are expressed as percent by weight of dry API CLASS H cementunless otherwise noted. The retarder employed, unless otherwise noted,was sodium lignosulfonate.

The mix water employed, unless otherwise noted, was potable city tapwater as available in Houston, Tex.

Unless otherwise noted, Thickening Time was determined in accordancewith the provisions of API Spec 10. Zero Gel Time and and TransitionTime were determined in accordance with Sabins et al, mentionedpreviously, and compressive strength was measured with an UltrasonicCement Analyzer (UCA).

                  TABLE 6                                                         ______________________________________                                        SLURRY NUMBER                                                                 MIX WATER.sup.1                                                                      33    34      35      36    37    38                                   ______________________________________                                        Polymer, %                                                                             0       0.6     0     0.6   0     1.4                                Retarder, %                                                                            0.15    0.15    0.375 0.375 0.4.sup.2                                                                           0.4.sup.2                          Temp deg F.                                                                            140     140     200   200   250   250                                Thickening                                                                    Time,                                                                         HRS:MIN          4:45          4:20        4:19                               Zero Gel                                                                      Time,                                                                         HRS:MIN  0:53    9:05    0:47  7:13  1:07  4:01                               Transition                                                                    Time,                                                                         HRS:MIN  3:33    0:05    0:14  1:05  1:02  1:07                               Comp Strength                                                                 HRS:MIN                                                                        50 psi  8:10    9:39    7:46  10:26 5:45  6:47                               500 psi  9:35    10:51   8:27  11:18 6:31  7:44                               24 hours                                                                      PSI      2591    2786    3175  2660  2090  1439                               ______________________________________                                         Footnotes Table 6:                                                            .sup.1. Slurries 33, 34, 35 and 36 were made using 40 percent mix water       and slurries 37 and 38 were made using 55 percent mix water.                  .sup.2. 0.2% sodium lignosulfonate and 0.2% tartaric acid.               

What is claimed is:
 1. A method of cementing a borehole which penetratesa subterranean formation said method being comprised of the stepsof:forming a cement composition comprised of hydraulic cement in water;placing said cement composition in said borehole adjacent saidformation; permitting said cement composition to set in said boreholewhereby a hardened mass of cement is produced;wherein said cementcomposition is comprised of water, hydraulic cement and an additive,said additive being comprised of a copolymer or a terpolymerpolymerization product of a first vinyl-containing monomer with one ortwo other different vinyl-containing monomers selected from a secondvinyl-containing monomer, a third vinyl-containing monomer and a fourthvinyl-containing monomer, wherein said first vinyl-containing monomer isa vinylamide morpholine derivative, said second vinyl-containing monomeris a vinylamide derivative, said third vinyl-containing monomer is anN-vinyl,2-ketoheterocyclic derivative and said fourth vinyl-containingmonomer is a vinylacid derivative; and further wherein said vinylamidemorpholine derivative is selected from compounds represented by thegeneral formula ##STR9## wherein R₁ is --H or --CH₃ and R₂ is --CH₃ or--CH₂ CH₃ and is positioned on any one of the four carbons in the ring;said vinylamide derivative is selected from compounds represented by thegeneral formula ##STR10## wherein R₃ is --H or --CH₃, R₅ is --H, --CH₃or --CH₂ CH₃, and R₄ is --H, --CH₃, --CH₂ CH₃, --CH(CH₃)₂, --C(CH₃)₃ or--C(CH₃)₂ CH₂ SO₃ X and X is --H, --Na, --NH₄ or --Ca1/2; saidN-vinyl,2-ketoheterocyclic derivative is selected from compoundsrepresented by the general formula ##STR11## wherein R₆ is --H or --CH₃,and m has a value in the range of 3 to 6; and said vinylacid derivativeis selected from compounds represented by the general formula ##STR12##wherein R₇ is --H or --CH₃, Z is --PO₃ Y₂, --SO₃ Y or --CO₂ Y, Y is --H,--Na or --Ca1/2 and n has a value in the range of from about 0 to about3.
 2. The method of claim 1 wherein said additive is present in saidcement composition in an amount in the range of from about 0.1 to about1.5 percent additive by weight of hydraulic cement in said composition.3. The method of claim 2 wherein said polymerization product is aterpolymer comprising said first vinyl-containing monomer, a compoundselected from the group consisting of said second vinyl-containingmonomer and said third vinyl-containing monomer and said fourthvinyl-containing monomer.
 4. The method of claim 2 wherein the moleratio of said vinylamide derivative, said N-vinyl,2-ketoheterocyclicderivative and mixtures thereof to said vinylamide morpholine derivativein said polymerization product is an amount in the range of from about 0to about 4.5 moles per mole of said vinylamide morpholine derivative andthe mole ratio of said vinylacid derivative to said vinylamidemorpholine derivative in said polymerization product is an amount in therange of from about 0 to about 4.5 moles per mole of said vinylamidemorpholine derivative.
 5. The method of claim 3 wherein the mole ratioof said compound selected from the group consisting of said secondvinyl-containing monomer and said third vinyl-containing monomer to saidfirst vinyl-containing monomer in said polymerization product is anamount in the range of from about 0.5 to about 4.5 moles of saidcompound per mole of said first vinyl-containing monomer and the moleratio of said fourth vinyl-containing monomer to said firstvinyl-containing monomer in said polymerization product is an amount upto about 0.55 moles of said fourth vinyl-containing monomer per mole ofsaid first vinyl-containing monomer.
 6. The method of claim 4 whereinpolymerization product is a copolymer, said vinylamide morpholinederivative is acryloylmorpholine and said vinylamide derivative is2-acrylamido-2-methylpropanesulfonic acid.
 7. The method of claim 5wherein said vinylamide morpholine derivative is acryloylmorpholine,said vinylamide derivative is 2-acrylamido-2-methylpropanesulfonic acidand said vinylacid derivative is vinylphosphonic acid.
 8. The method ofclaim 5 wherein said vinylamide morpholine derivative isacryloylmorpholine, said N-vinyl,2-ketoheterocyclic derivative isN-vinyl pyrrolidone and said vinylacid derivative is vinylphosphonicacid.